1. Field of the Invention
This invention relates to a starting device for internal combustion engines; and more particularly to a starter strip operable to initiate movement of the drive shaft of a small engine during starting.
2. Description of the Prior Art
Starting mechanisms for internal combustion engines, for example small engines used in lawn and power applications, and even smaller engines designed for model planes and the like, need improvement. These mechanisms are typically of the rope and pulley type, and when used present the manufacturer and user numerous problems.
Some of the problems presented by conventional starting mechanisms include broken rope, tangled rope, spreading of the pulley sides, inconsistent pulls, jamming of the rope, wear on the rope, the expense of attaching handles, the attachment to the pulley, and the like.
A major complaint with conventional starting systems is that they are prone to failure and expensive to repair. Servicing these systems oftentimes entails labor intensive operations and testing, as well as added expense in materials for parts of the mechanisms involved: rope, knotting, handles and pulley design. Design requirements specified for rope systems make them difficult to construct and do not allow for starting mechanism that afford a consistent, non-obstructive wind up or pull.
It would be desirable to provide an improvement to the conventional rope and pulley mechanisms, which would alleviate these problems.
The present invention provides a starting device having a strip, which is connected to the pulley of a pull start mechanism. In one embodiment, the strip is composed of a high performance polymer, such as nylon, preferably Capron(copyright) nylon 6 from Honeywell International Inc. and can be provided with an integral handle, such as by molding. Preferably, the strip is made by injection molding, extrusion or other methods from a high strength material. The strip is connected to the pulley by a connection means on its distal end. The strip is designed to fit neatly in a coil around a pulley hub.
More specifically, the invention provides a starting apparatus for internal combustion engines, comprising an elongated flexible starter strip provided with a handle on a first end and a connection means on a second end. A housing partially encloses the apparatus and is provided with an opening for receiving the starter strip. A receptacle, provided with a central hub and a post, is fixed within the housing. Rotatably positioned on the hub is a starter pulley provided with a channel for storing the starter strip. The pulley has one or more slots for securely receiving the connection means. When thus received, the first end of the starter strip is secured to the starter pulley and the elongated starter strip is wound around the starter pulley within the channel. A spirally wound spring having inner and outer ends are provided for rewinding the starter pulley. The spring is positioned within the receptacle with its inner end fixed to the pulley and its outer end fixed to the post. A ratcheting means is provided for connecting the pulley to the drive shaft of the internal combustion engine. The ratcheting means provides for uncoupled rotation between the pulley and the drive shaft when the pulley rotates in the opposite direction of normal drive shaft rotation. Coupled rotation between the pulley and the drive shaft is also provided by the ratcheting means when the pulley rotates in the direction of normal drive shaft rotation. With this arrangement, the handle is pulled causing the strip to unwind. The spring becomes wound and the pulley rotates, causing the ratchet means to engage the drive shaft and start the engine. Upon release of the strip, the spring unwinds, causing the strip to be rewound on the pulley.
The starting device of this invention provides an efficient pulley design since the starting strip lays flat and exerts substantially no lateral pressure against the walls of the pulley. When constructed from a high strength plastic material such Capron(copyright) nylon 6 resin from Honeywell International Inc., the strip lasts longer than a conventional starter rope. In addition, with such construction, the starter strip does not fray and affords a storing mechanism that is much cleaner than a conventional rope system.
Advantageously, the present starting device can have an integral pulley handle. With this feature, the device has fewer parts. It is easier to assemble, owing to the absence of attachment points typically required for actuation with rope or cords (which are usually knotted). Lateral pressure on the pulley is virtually eliminated. Conventional rope/pulley constructions can be replaced by lightweight, inexpensive rewinding devices that facilitate starting in an efficient, reliable manner. The propensity for snagging, wedging or knotting of the starter cord is replaced by a consistent, non-obstructive wind up or pull.
Rope breakage is eliminated. A constant grab and pull accompanies each starting attempt. Engine powered units can be redesigned into units that are smaller, lighter, less expensive, more efficient and much more reliable in operation.